INFLUENCE OF NONLINEAR BLADE DAMPING ON HELICOPTER GROUND RESONANCE INSTABILITY.
The lagging motion of each helicopter blade is assumed to be of equal amplitude and equally apportioned phase, thus allowing a simplified analytical method to be used to calculate the ground resonance instability of a helicopter model with nonlinear dampers in both the landing gear and blades. The geometrical nonlinearities of the blade lag motion and the influence of initial disturbances on ground resonance instability are also discussed. Finally an experiment is carried out using a helicopter scale model. The experimental data agree well with analysis.